In the field of analytical chemistry in particular, various means are well known for analyzing liquids such as water or wine, for example to determine, in particular, the chemical content of said liquids, and more specifically to determine whether pollutants such as fungicides are present.
Test strips or chromatography are among the systems which are most commonly used.
Test strips do not allow traces of fungicides to be detected at the level of several ng/l, and the disadvantage of chromatography is that it can take a long time and it be costly.
The most commonly used method for measuring fungicides is high-performance liquid chromatography or HPLC. However this analysis requires numerous preliminary operations consisting of extraction, purification, concentration and potentially drying steps.
Other newer methods have been used to avoid the sample treatment step (extraction, purification, concentration and drying) in order to reduce the analysis time and to reduce the significant quantities of solvent used for extraction.
We can cite the example of fiber from Solid Phase Micro Extraction or SPME. This method is based on using a 110 μm silica fiber coated with a 7 to 100 μm thick adsorbent over a length of 1 cm and located at the end of a syringe. The needle pierces the septum of the vial containing the sample and the fiber is immersed within the sample for the extraction of compounds. The fiber is introduced into a chromatograph in gas phase after a given extraction period (Pichon V, 2012). Extraction sur phase solide pour l'analyse de composés organiques [Extraction in solid phase for the analysis of organic compounds] [P 1420]. Techniques de l'Ingénieur, base documentaire Chromatographie et techniques séparatives [Engineering techniques, chromatography document base and separating techniques].
The SPME fiber requires several steps to be implemented before the fungicide can be determined: ten-minute extraction followed by a chromatographic analysis which lasts at least 30 minutes.
We are also aware of sensors consisting of “molecularly imprinted polymer” or MIP. This includes the American patent applications US 2008/0144002, US 2012/0288944, US 2004/0126814 and the scientific publication “Molecular-Imprinted, Polymer-Coated Quartz Crystal Microbalances for the Detection of Terpenes (Anal. Chem. 2001; 73 4225-4228). In this specific case, transduction is performed using an acoustic sensor within the sensitive material.
Document US 2008/0288944 describes a sensor consisting of a molecularly imprinted polymer for the detection of a specific targeted inorganic ion. This sensor consists of one or more molecularly imprinted polymer beads with a macro-porous structure containing a plurality of cavities called complexation, said cavities contain cationic ligands which are spatially oriented in order to selectively receive and bind to a specific targeted inorganic ion intended for detection. The sensor, associated with a light source such as an ultraviolet, infrared or visible light, allows the luminescence of the molecularly imprinted polymer beads to which a particular targeted inorganic ion is fixed to be obtained.
Document US 2012/0288944 describes a procedure for detecting a tracer molecular structure in a fluid using a sensor consisting of a molecularly imprinted polymer. The procedure consists of placing a molecularly imprinted polymer in a crosslinked star into contact with the fluid, then correlating the change of color in the fluid with the quantity of the tracer molecular structure within the fluid. The device has polymeric arms attached to a core, and the core has molecular-size cavities suitable for selectively receiving and binding molecules with a tracer molecular structure, said core also has a colorimetric indicator. The movement molecule is selectively removed from the molecularly imprinted crosslinked polymer by exposure to the tracer molecular structure within the fluid, therefore indicating the presence of the tracer molecular structure within the fluid based on the loss of color.
Document US 2004/0126814 describes a sensor for the detection of a target analyte using a molecularly imprinted polymer (MIP) imprinted with a target analyte. The MIP can be used as a working electrode in electrochemical impedance spectroscopy, either by coating a substrate or by being pressed onto a disk. The sensor can also use the molecularly imprinted polymer (MIP) to detect a target analyte using other electrochemical procedures.
The scientific publication “Molecular-Imprinted, Polymer-Coated Quartz Crystal Microbalances for the Detection of Terpenes (Anal. Chem. 2001, 73, 4225-4228) describes a quartz microbalance which allows terpenes to be detected. The microbalance is made from two conductive electrodes with a piezoelectric substrate on both sides covered with a molecularly imprinted polymer layer. When an electrical current is applied, quartz located between the two electrodes on the substrate vibrates producing an acoustic wave through the sensitive material. However this quartz can only oscillate at one frequency when current is applied to its terminals. The current in the electrode terminals can be transmitted in an undesired way to the quartz terminals, for example by salt crystal conduction in a liquid which causes false detection of terpenes. Furthermore, this device only allows one single measurement to be made indicating the presence or absence of terpene, and does not allow the presence of terpenes to be quantified.
The invention's technical problem therefore consists of proposing a device for the detection of an analyte in a liquid allowing the presence of an analyte to be detected in a liquid in a rapid and reliable manner.